I. How are renal cysts formed? Most simple cysts are mostly formed later in life, initially due to obstruction of renal tubules blocking the formation of small diverticula, then fluid keeps accumulating and the diverticula keeps increasing in size to form cysts. Polycystic kidney, on the other hand, is mainly due to congenital hereditary factors, with genetic defects, resulting in numerous cysts of different sizes on both sides of the kidney. In Chinese medicine, it is believed that kidney cysts are mostly due to congenital genetic or acquired loss of nourishment, damaged kidney qi and disharmony of blood and water in the kidney, resulting in internal cystic diseases. Is it dangerous to have cysts in the kidney? Most of the kidney cysts are asymptomatic and usually do not have great impact on human health. Some patients may have the following symptoms due to the increased pressure in the cyst, cyst bleeding, concomitant infection and other causative factors: 1. Discomfort or pain in the waist and abdomen: the pain is characterized by hidden pain, dull pain, fixed on one or both sides, radiating to the lower abdomen and lower back. If there is intracapsular hemorrhage or secondary infection, the pain will suddenly increase. If combined with stones or blood clots blocking the urinary tract after bleeding, colic may occur. 2. Hematuria: It can be microscopic hematuria or meatus hematuria, which can be periodic. The back pain increases during the attack, and can be triggered or aggravated by strenuous exercise, trauma and infection. 3.Abdominal mass: It used to be the main reason for patients to visit the clinic, and the enlarged kidney can be palpated in 60% to 80% of patients. 4.Hypertension: It can be caused by the cyst compressing the kidney and causing ischemia in the kidney, and the incidence of hypertension is higher when the kidney function is decreasing. 5.Proteinuria: It can appear in some patients, and the amount of urine protein is usually not much. 6.Decreased renal function: Due to the long-term compression of kidney parenchyma by cyst, the normal kidney tissue shrinks significantly and the renal function decreases progressively. 7.Malignant transformation of kidney cysts and formation of kidney cancer. About 3% to 7% of kidney cysts may become malignant and need timely detection and active treatment. Most small cysts do not need special treatment, but any of the above symptoms will have an impact on health when the condition is severe. Our advice is to decide whether it is time to “do something” about your cysts under the guidance of a professional doctor. Third, do kidney cysts need treatment? What are the main treatment methods? If the cyst is small and the patient does not have any uncomfortable symptoms, no treatment can be done for the time being; however, it should be reviewed regularly to see if the cyst continues to grow and how fast it is growing. If the cyst is symptomatic or large (diameter >100px), laparoscopic renal cyst decompression is preferred after malignancy is clearly excluded – the “roof” of the cyst is lifted off to prevent the accumulation of cystic fluid. The advantage of this procedure is that it is less invasive and has a lower recurrence rate. When the cyst is suspected to be malignant, it should be promptly investigated by surgery, and if necessary, the occupied kidney should be completely removed. IV. How to determine the malignant change of renal cyst? Clinicians can grade renal cysts by ultrasound and CT performance, and the grading system is called “Bosniak grading system”. Grade I cysts: simple benign cysts with thin wall, no separation or calcification, and watery fluid; Grade II cysts: benign cysts with small separation and or calcification, and no enhancement of the separation; Grade III cysts: thick wall, multiple separation and calcification within the cyst, and enhancement of the separation, more than 50% of the cysts are malignant; Grade IV cysts: malignant cysts with enhanced soft tissue components within the cyst. For grade I-II cysts, observation follow-up is an option, while grade III-IV cysts should be surgically explored and removed as soon as possible. Therefore, if you find an extra cyst on your kidney during physical examination, please make sure to come to our hospital and let the professional doctor read the film for you!